A STUDY OF THE ABRASIVE WEAR IN THE POLISHING OF POLYPROPYLENE USING X-RAY PHOTOELECTRON-SPECTROSCOPY

The study of the abrasive wear of polymers is important both in the preparation of polymers prior to joining and in the techniques used to expose surfaces and interfaces for examination by a variety of analytical methods. In this investigation by X-ray photoelectron spectroscopy, the influence of the atmosphere on the chemical damage to polypropylene during the process of abrasion was examined, looking in particular for evidence of surface oxidation. The extent to which particles of abrasive, alumina in the present case, are introduced into the polymer was also examined. In this case a comparison of dry and lubricated polishing was made. The latter was found to be the more damaging, with damage increasing in relation to the solubility parameter of the solvent (lubricant). The work has shown that the simple cutting of the surface by an uncontaminated knife is the cleanest method for the exposure of the internal surfaces of the polymer. No advantage is gained by shaving the surface in argon or vacuum over that produced by shaving in air. Dry abrasion using alumina is effective in removing pre-existing contamination, but significant quantities of alumina are introduced into the surface. One effect of this is to produce a large oxygen signal that would make subsequent analytical interpretation difficult. As indicated above, lubricated abrasion seems quite unacceptable.